fix: leave space for autohide taskbar for frameless maximized window

[zcbenz]

Description of Change

Close #18310.

When autohide taskbar is enabled, the window needs to leave some space for it when maximized. Chromium already does the trick for normal window, however it is not doing the trick for frameless window.

Since Chromium is deprecating Chrome Apps and it does not use frameless windows in other parts of code, I don't think Chromium will fix it for us, and patching Chromium may not be a good idea since all frameless window code may gradually stop working.

So in this PR I followed Chromium's trick on resizing the maximized window to leave space for autohide taskbar when using frameless window. It should be able to work through time no matter what Chromium does with its frameless window code.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fix autohide taskbar not showing when frameless window is maximized.

[ckerr]

This patch seems large at first but most of the lines are just mechanical -- either adding in the Chromium code, or adding the shims to ensure it gets code, e.g. separating the X and Win implementations of Maximize.

Overall LGTM. I agree with the rationale in the description for copying in what we need.

[release-clerk]

Release Notes Persisted

Fix autohide taskbar not showing when frameless window is maximized.

[trop]

I have automatically backported this PR to "6-0-x", please check out #18373